Automatic telephone system



April 7,1925- H 1,533,079.

R. G. RICHARDSON l AUTOMATIC .TELEPHONE SYSTM originan Find ms, 1920 ssneetsfshnt 1 Badi-zeg HEIDI-fardeau.'

April 7, l925- A 1,533,079 R. G. RICHARDSON AUTOMATIC TELEPHONE SYSTEM'I original Filed nb. fr, 1920 InUEL-z m" Hndney E. Hzchardsan IlHIIApril 7, 1925. 1,533,079

R. G. RICHARDSON AUTOMATIC TELEPHONE SYSTEM Original Filed Feb. e, 19203 Sheets-Sheet 5 a//er .B/ock Patented Apr. 7, 1925.l

UNITED STATES PATENT OFFICE.KA

RODNEY G. RICHARDsON, or CHICAGO, rritrivors, vAssrenon ro Aaron/LarioELECTnIC COMPANY, or CHICAGO, ranno-1s, a Coaronafrron or iLLINOIs.

AUTOMATIC :TELEPHONE SYSTElWI.

Application 1e i February 6, 1920,Seria1 No. 356,803. Renewed July 16,l192.4.

To all whom t may cof/wem Be it known that I, RODNEY'G. RICHARD- SON, acitizen of the United States of America, and a resident of Chicago, CookCounty, Illinois, have invented certain new and kuseful Improvements inAutomatic Telephone Systems, of which the following is a specification.A

My invention relates in general to automatic telephone systems, but isConcerned more particularly with automatic party line telephone systemsin which means is provided at the exchange for selectively signallingthe different stations on the party lines; and the object of theinvention may be stated to be the provision of a new and more eflicientVand flexible systenrof this kind than has hitherto been available.'

In my prior United States Patent No.v

1,528,343, issued March, 1925, I have described a system of party lineselective signalling in which each party line is accessible by way of asmany called line branches as there are stations on the line, thelineandits several'branches being connected at an `hiternfiediate distributingframe, and V in y which frequency selecting connectors are used whosefrequency selecting operations are controllable over any called linebranch connected with the frequency selection be- `Ying determined bythe manner in which the branches are connected to the line at saiddistributing frame. In a system of this kind the different Call numbersor telephone numbersl have no liXed relation to each other, or to anyparty line, or to' any vparticular kind of ringing current; and such asystem therefore provides for handling Changing and uctuating party linebusiness with a maximum of convenience both to the company and to thesubscribers, while securing a maximum eliiciency in the utilization ofthe central ofce switches outside cable plant. y l

The system above described, however, provides for full metallic circuitringing on the harmonic principle and on that account the circuits arenecessarily 'somewhat corn-V plicated. I have` found that by connecting'the ringers at two of the stations on afour party line fromvone side ofthe line to and in the cation above referred to, in which the deg siredresults are obtained inv al different manner and by` using different andless complicated circuit arrangements. f

Having stated in more or less general terms the objectof the invention,the appa@` ratus and improved circuits used to Carry out the samewillnow be explainedv more in detail, reference being had to the'accomV- panying drawings, colnprising'Figs. l, 2,.

and 3, which are circuit diagrams showing the essential features of a.telephone system embodying the invention.

Referring `to the drawings, the substation A, Fig. yl, is an ordinaryautomatic substation, which, although shown for convenfv ienrce as'beingindividual to the line,V may equally7 well be a party line substation.yIt

comprises the usual talking equipment and ringer, and also acallingdevice indicated by the reference character S, through themediumvof Iwhich the subscriber controls the entrai oliice switches.

. he line conductors 1l andl?I extend to' the exchange where theyterminate in the rotary line switch C in a manner more clearly shown inFig. Sgin the case of a called line. rIhe vlinel switch C may be brieflydescribedv as a rotary line switch whose movable terminals or wipershave no normal position', and which have movement in a forwarddirectiononly; The construc-l tion of a line switch of this type iswell, known in the art, and its function, also well understood, is toextend the'associatedline when callingto an idle trunklin'ie.'v For thispurpose,ja plurality of these individual line switches may be givenaccess to a group of-` trunk lines *extending to first selectorswitches. One ofthetrunk lines to which the line switch lC haslaccess isshownin the which .gis a vertical and rotary selector switch of theusual construction. The selector D, together' with a plurality ofsimivlar selectors, has access toa plurality of Ygroups Aof trunk-l-ines, the trunk .lines of eachgroup terminating in a -group of con- Ynector switches. One of the trunk lines to whichmthesselector D hasaccess is shown eXtend'ingto "the'connector E, Fig. 2. The connector E'likewise 1s =a. `vertical Vand rotary switch of well knownconstruction,

and, except for the circuits having vto do with the selective ringing,is of the usual type which is in common use. It is understood Vthatsecond and third selectors Amay Vbe-used if desired according `to thecapacity ofthe exchange; land itlmay be stated that the system oftrunking employed is the same `as the system ycommonly referred toasgthegpercentage trunking system'. A

F ig. .3, I have shownin detail the manner in which al party line isconnected for j rboth.incoming and outgoing `service at the main and'intermediate distributingframes.

The ylayout shown maybe described briefly as follows:v The. four partyline comprising conductors '201 vand 202, which has the four`slibstation A to A4, inclusive, connected in bridge thereof, is.assumed to enter the exchange tby way of cable Vpair B2 which. isterminated on the cable side of the main distributing frame in the usualmanner.

Thisjcable pair Vis connected by means of a` Vjumper 'with any desiredpair on the switchboard side ofthe main distributing frame,.

and may Vbe terminated on the switchboard side of the main distributingvframe as shown, or on the vertical side of the intermediatedistributing frame, it is immaterial u vh'ic-h. The jumper on the maindistributing'frame having been run, it will be evident vthat the 'partyline Vshown will be connectedwfor outgoing servicey by way of theindividual line switch C", which has l access to.,

K IaV plurality of Vfirst selectors similar to? the first 'selecto-r D.The line-is-connee'ted for incoming service VVVat4` the' intermediatedistributing frame.

On* thel horizontal side of `this frame .aretfermin atedy the normalcables comings-.from allAv the lconnector groups in the exchange., Thesecable pairs are preferably A arrangedin consecutive order onthehorizon-tallside of the frame in accordance lwith ftheL-call numbers,and the terminal sets should`. beY .so numbered.l This is yshownkclearly .in the drawing wherein the firstV sets cordance with theynumber of the group according tov any desired numbering scheme;

while the other foursets of each groupy are preferably marked inaccordance with the ringing characteristics of the :four stations ontheline. As shown in Fig. 3,'th'e1markingsl indicate 33 and 50 cycleringers connected from the positive vand negative sides of the line .toground. These markings are not necessary but are'veryconvenient.YV Themanner of connecting 4"the line lfor incoming service will now beapparent. Terminal set 1 on the vertical. side 'of the intermediateframe `is connected by means of the triplex jumper 204: with .the upperterminal setof some vacant group von an idler block as for example, thegroup shown, which is .group #1. Then the other four terminal sets oflthisgroup areco-nnected by means of v:jumpers 205, 206, 207 and `208with the terminal sets on 'the horizontal side of the intermediateframeV which correspond 'to the call `numbers whichV have been asignedto the different stations on the party line'. y It is vto Abe clearlyunderstood that any call numbers whatever may be used. The line is nowcompletely'conne'cted for both incoming and outgoing service. l Y

I will now ldescribe vthe operation-ofthe circuits involved withthespecial object of loisv explaining the method `by which the'.stations on a lineare selectively signaled. For this purpose it. Vwillfirst be assumed that theV g subscriber at substation vA desires to callthe subscriber at substationA., whose ringer, tuned to theSS cyclefrequency, is connected from line conductor 201 to ground, and whosetelephone number, therefore, when the line is connected as shown inthe'draw-; ing, willbe #111.' When'the receiver is removed fromthe-*hook rat substation A,.a circuit vis 'completed over thelineconductors 11 and 12 for the yline relay 14 of the line switch C.Upon energizing, the line relay completes a cir'cuitextending throughthe switching relay V13 and the stepping magnet v Y 15 in series atV itsarmature; 20, and at its armature-19 connects the test wiper 26 to the,`above circuit at a pointV -midway between. the switching' vrelay j andVthe Y said"A stepping magnet. The operation now -depends upon`whetherthe-test contact with which the test wiper V26 is in engagementis busyoris not busy. If this test Contact is busy it 'will have aground potential upon it,

(lll l the switching relay 13 will be short circuited, and the steppingmagnet 15, which interrupts its own circuity will operate as a buzzer toadvance the switch wipers -27, inclusive, step by step in search oi anidle truiil-I line. rl'his operation will continue as long as the testwiper 26 engages grounded oi busy test contacts. However, we may assumethat iii the present case when the call' is initiated, the selector' l)is idle and the test contact 31 therefore is not grounded` Under thesecircumstances, when the line relay 14 is energized, the switching relay13 is energized immediately afterwards, with the result that the lineconductors 11 and 12 are disconnected from the winding ot the line relay14 and from ground, respectively, and are extended by means ot armatures16 and 18, wipers 25 and 27, bank contacts and 32, and armatures 63 and'85 and their resting contacts to the upper and lower windings of theline relay .50 oli selector D. p

Immediately uponthe e.;tension ot the line as above described the linerelay will be energizedy over the line c- 1cuit and will close thecircuit ot the slow acting release relay 51. Upon energizing, relay 51prepares the circuits of the selector for the vertical operation in theusual manner, and at armature 58 completes a holding circuit extendingback to the line switch C over the following path: ground at G2,-workingcontact of armature 58 and the said armature, conductor 90, test contact31, test wiper 26, armature 17 and its Working contact7 winding of theswitching relay 13, and the winding of the stepping magnet 15 tobattery. It is understood that the above circuit is established beforethe slow` acting line relay 14 has had time to deenergize.

The calling subscriber may now operate his calling device in accordancewith the iirst digit of the desired number.` A series ci interruptionsin the circuit of the linerelay 50 is thereby produced, causinglcorresponding series ot deenergizatioiis of `the said ine relay, whichat each deenergization sends a. current impulse through the slow actingrelay 52 and the vertical magnet 56 in series to battery. By theoperation ot the vertical magnet the selector shaft israised step bystep until the wipers 7 O-7 2, inclusive, stand opposite the desiredlevel ot bank contacts. The slow acting relay 52 is energized in serieswith the vertical magnet, retaining` its armature attracted throughoutthe vertical movement of the switch, and upon the ture 60, and atarmature 61 establishes alocking circuit for itselt. At the end of thevertical operation` of the switchthe slowacting relay 52 is deencrgizedandL closes the circuit ot the rotary magnet, which is thereuponenergized to advance the Wipers 72, inclusive, into engagement withthefirst set of bank contacts in the level oppositewhich they wereraised. The rotary magnet also breaks the circuit of the stepping relayl 53, which a co ugly is deenergized to break the circuit 'of the rotarymagnet, whichV it, and the 'stepping` relay 53 will be energized againover a` circuit which extendsY from the grounded test contact by way ofthe test wiper 71, armature 64 and its? resting contact, the interruptercontact'ot the rotary magnet, the ott'. normal springs` G2, and thewinding'of the stepping relay,

53 to battery. The stepping relay will there? tore again close thecircuit of the rotary magnet 54, which will` operate to advance theswitch wipers into engagement with the4 next set oli' bank contacts.This operation. by which the stepping relay and the rot-ary nagnet are`alternately energized and de energized willl continue as long as thetest wiper 71 engages busy orv grounded test contacts. In the presentcase vit will be assumed that the trunk line shown inthe drawings is thefirst idle trunk line, and when, therefore, the test wiper 71 arrives attest contact 74 and the rotary magnet is deenergized, the

stepping relay 53 will not again be energized; l i

but instead the switchingv relay.. 55, which hitherto'has been shortcircuited,rwill be operated by current flowing over `the following path:grounded conductor 90, winding y ofthe switching relay 55, interruptercontact of the rota-ry magnet, oli' normal springs 62, and thewinding oithe steppingrelay 53 to battery. Owing to the high, resistance of theswitching relay 55',v the stepping relay 53 is not operated. Uponenergizing, relay 55 disconnects the incoming line conductors from thewindings of the line relay 50, and extends them by way of armatures 63and 65 and their working contacts, wipers 70and 72, bank contacts73 .and75, conductors 76 and 78, and normally closed contacts ofthe back bridgerelay 100 to the upper and lower,v windings ot the line relay 101 oitthe connector E, Fig. 2. i

the connector E, the line relay 101 isenergized over the line circuitandcompletes a circuit for the slow-acting'release relay 102.'

Upon energizing, relay 102 prepares the cire cuits of the connector forVoperationin its vertical inoveinent, and also closes a holding Thecalling line havingebeen'eiitended to,

iiov

circuit extending back-to the` selectorl D,

Iwhich may be traced as follows: ground at Y 'contact o'arinature 116andsaidj afin ure, iconductor77, test Contact V711, test wiper 71, zandarmature 64 and its working contact to vconductor 90, where it joins thepreviously 'described holding circuit entendingba'ck tothe line switchC, and serres to niaintai'nvrelays V55 and 13 energized.

When the calling Subscriber operates his calling device 'in accordancewith the Ynext digit in the desired `n-umbeiya series of interruptionsis produced in the circuit ci the line Yrelz'i'yglOl, V'whlchaccordingly de'energizes a corresponding number of times. At eachdeeiier'gi'aationjthe line relay transmits a cur-v rent :impulse throughthe vertical magnet 111 ver the,followingcircuit: ground at G, armature115 Tand its restingcontact, armature 117 `and yits working contact, offynormal springsllO 'andV 152, 'winding of the .slow acting relay 103a'ndthe 4winding of the.

vertical magnet 111 tobattery. This is the circuit "over 'which thefirst impulse is trans- V mitted. theV upward step of the switch shaft,however, the oit' normal springs 'are shifted, and theVc-i'rcuit extends`fronrthe vworking contact ef armature 117 by 'way f' oli' normalcontact springs 150 and 151, armature 118 and its working contaet (relay103 being nowen'ergized), winding of relay 103, and the winding of the yvertical magnet 111 to battery. By the operationof theverticalmagnetrv'the switch shaft is raisedstepfby step until the wipers 16C-'162,`inclusive,standY opposite the de- L sired level of bank contacts. Atthe end 'of the vertical lIn'ovenfient ofjthe switch the slew-actingrelay deenergized and prethe switch kfor operation in its rotarymovement. u n v e y The 'calling subscriber may now Voperate Vhis4calling device in accordance with the last digit inthe number,thereby'producing as Y ybefire a series' of interruptionsin the cirfit.

yce'

cuit el: the line relay 101. each resulting deenergizatien ftheline,relay now sends a vcurrent impulse thrughthe rotary magnet 113 'over thefollowing circuit: ground at G4, arjIfn'a-tureV 115 and its restingcontact, armature 117 andnits working contact, 'off normal springs 150vand 151, 4,rniatilre 118 and its resting contact, restingV contact ofarmature124 and the` saidl armature, resting citaet f armature 135randthe said armature', rand the winding vof the rotary magnet 113 tobattery. In response to these irnpulses the rotarygmagnet operates torotate the wipers 1160462, inclusive, intofengage-` Vment with thedesired Vset of bank contacts `in the level lopposite which they wereraised,

Since, inthe present case, the desired station is 111, thewipers willhave been raised oppositie.y the first level, and they will be rof tatedin'to engagement with, thehiirst setl off contras iff 'this level,prjqqacts indicated The slow acting relay 106 is KVener-giZed parallelwith the rotary magnet and retains its armatures attracted throughoutthe 'rotary movement Aof the switch. Atv armature 128v relay 106connectswthe test .wiper161 to the winding of the ybusy test relay1.05'and at its armature 129 relay 106 closes a shunt varound 'armature121 of the Vtest relay and its resting Contact to guard against thepossibility of the said'test relay V.being nelmen.-v tarily energizedwhilexthe testuwiper 161 is passing over busy testrkcontacts.l Il thecalled line is busy when the testfwip'ery 161 arrives at the testcontact associatedr therewith, as, for exan'iple, `the test Contact 172.the test relay 105 will be energized, and

when the slow-acting. relay 106 deenergizes Let it be assumed, however,that the called' line is idle when the connector E is operated as beforeexplained. yto establish connection therewith. Under these circumstanceswhen the switch wipers 160-1'62, inclusive, are

brought to restv in engagement with; bank contacts 1714173, inclusive,the test relay will not be energized, for the test Contact 172 will notbe grounded; and when the slow-acting relay 106ydeenergizes,4 upon thecessation of the rotary/movement, the Etollowing circuit will becompletedzpground at G3, working `contact of armature 116 fand the saidarmature, conductor 77, armature- 123 vand its resting Contact,upper'winding of switching relay 107, upper winding of c frequencyselecting relay 108, resting contact of ar1nature128 and the saidarmature,

testwiperll, test contact 172, conductor 215, lcenter terminal -ofterminal'set 111 on horizontalY side of I. D. F.,"s'tran d `of jumper205, center terminal of set marked 331 ofy idler block group `f7-L1,resistance 220, center terminal `of upper'set of idler block groupk 217,winding of switching relay 13 of line switch C vand the winding of thestepping .12e 1, strand of jumper 2041 centerteminalfof-- the setassigned to pair #l on'the vertical side of the I. D. F., conductor 216,conductor` magnet 15 to battery.- By the closure ofthe above, circuitvrelays 107 and 108 of the vconnector arey connected in series over thethird conductor of the called branch.l .with the switching relay 13 ofthe line 'switch C, and

became the latter relay is energized, Abeing operated only about haltway,"howevenl due to the fact-that the line relay 14; is not energized.As a result, the conductors 218 and 210are disconnected from the :linerelay 14 v:and from ground, respectively. At the connec tor, relay 108is'not energized jbccause of the tact that resistance 220 is includedyin the circuit. Relay 107, however, is energized and establishes|locking circuit Jfor itself at Varmature 184, opens *the rotary magnetcircuit at its armature 135, connects direct ground to the test wiperl161 at armaturel 188, prepares a circuit for the ring cut-oli relay 104at armature 132, and. at armature 136 completes the ringing circuit forsignalling the called station. The Acomplete `.ringing circuit; overwhich alternating'current from the l33 cycle generator 'flows out overthe lower side of the line Vcircuit and by way oit' line conductor 201and the ringers atst'ations A and A2 to ground, whence the circuit iscompleted by ground return tothe other'side of the grounded generator,is not difficult and will"not need'to be traced out in detail. It isunderstood, of course, that theringers at Stations A and A2 are-tuned to33 andy 50 cycles, respectively, and that the ringer at station A2 willnot yrespond in the present case.

Before proceeding lfurther, attention .is called -to the relay 221 whichis associated with idler block group #1,'Fig- 3, there being a similarrelay for each of the other groups. This relay is energized in parallelwith the switching relay 18 of line switch C both on incoming andoutgoing calls vand has the func-tion of short-circuiting .theresistance 220, which operationis necessary yin order to make lall fourbranches of theline test busy. viheneVer ther-line is called way of oneof the 33 cycle branches it is essential that relay 221 should notoperate before the switching relay l107 of the connector, as otherwise afalse operation ofthe marginal relay 108 might occur, resulting fromtheMshort-circuiting of 4resistance 220 before relay 107 connects directground to the test1 wiper. Relay 221, therefore, is made slightly slowto pull up bymeans of a copper slug or sleeve. It is noted that ytheslow action is required only when the resistance 2,20 is included in thecircuit, and atsuch times the presence ofthe resistance assists inproducing the desiredresult.v

`When the called subscriber at substation A removes his receiverinresponse to the ringing of his bell, the ringingvcircuit to ground isbroken by the hook switch ,and the two line conductors are closedthroughthe receiver and transmitter. The return path for ther-inging current isthereby completed over line conductorv202, the upper side ofthe linecircuit in the cxchangejthe upper winding ofthe lring cut-oli relay'104,

. and h2 The tehfe'ihihtel at .the tion fie non' ,ehpphed Frith Currenten@ 'the exeheee'e' .hehhery to cfoead- To lieg oeeoff relierie'theletoeieh ized ly @went the barema se with the 33 Ycycle generatororth B eeeooieed ihelleivth, and .hronattteehhs he @relatore 120,.eetahhehee .e `'loehfooa oirout through ite. lower annelies. lei'1.0.5.It also disconnects `its upper nwindi gan" ringing oohrehhgehelet-or, et @matures 1 and 121 and at the working icontacts veel-.hie lerhehlfee oohaeleteefthehel @uit hy .Coeneohne the eoadilotacoming line circuit lwith thej'linve' w1 l'- thrash ehe eiedhee of thedoable ,relied het. bridge relay 100 Ain the ,usual manner. on'

no such devices arel shown iny thel nt system. A* -K A p The `desiredconnection has v`now been cuit is shown in 4 heavylineggafiglbeiiiglhgli 13 ere' deehefehed; thereby ,reetorlle .the selector andvlineswitch'tonormalyalsb ."The selector is olf v.course restoredjbyuthefrel'ease magnet :57; whilev the wipers `off the if" switchremain Iwhere they fare, 4and simply `disconnected "by thedieenergizhation of the switchinglrelay l' Y A hlef exrlehetoh will vnewhegiven of the operation of selectiyelyh'signalling other seems konehe'i.1e1.efig,.

that station A2 is called,v.the xringefr'atwt station bein `connected.fr brny thefpositiyfze Side of the lheho growth eeethef ringer atstation A", but VAbeing tuned td'th 4,0 eyole frequency *Whenooifheotedhe' the telephone number of stationris The operation of thevswitches nislthel,same as has been described, except-that since`'thenumber called is'121, lthe connector Ewwill establish connection with Ythefcalledlinehy way of bankcOntaGts 1.174, 47,17 'fa'nd' F170, theterminal l set on the-hori'zontalsid oftlie I. which is-numb'ered 1241,juinpertlb, and the'50 cycle positiye-terniinalset otiiillei' leo.

block group #iL-this latter set being marked 50p in fthe drawing. YAtthe end `of the rotary movement Yor' the switch, when the f slow actingrelay 106 deenergizes, a Circuit is'co'mpleted for the relays 107 and108 of theV connector inyseries'with the relays 221v and 1,3 (theseVlast two beingin parallel),

.which is thelsame Vcircuit as was described l in 'theV case wherestationk A- was called eX- krcept that it'does not includerresistance220.

Itjfollovvsv that since the Vresistance 220 is not included -in thecircuit," the marginalrel l'lay 108 atthe connector will be energized atthe same time that relay 107 is energized,

'Relay 108 establishes a locking vcircuit` through its lower winding atarmature 144,'

l r andat its armature 146 changes the ringing circuit over tothe 50cycle generator. It Awillbe evident, then, that during the signallingoperation 50 cycle ringing current will beV transmitted over conductor201y of the called line to operate the50 cycle'ringer at A station yA2."

`The ringeij's at 'stations/A3 andA*` are also tuned to the 33 and 50cycleirequencies, re-

spectively, butare connected trom conductor 202, orthe negative side ofthe line, to ground.` Referring to Fig. 3, it will be ob# Lserved thatthere is a reversal inftlielin'e connections between the positive-andinegative terminal sets of the idler block group shown..Itfollowsthatif either telephone number 131 or 1111 is called, theringing` current will beprojected out over line concluetor 202 andthrough the ringers at stations VA Sflild A4 to ground. HWhether 50cycle Y Aringing current or 33 cycle ringing current isusedy.willvdepend onk Vwhether the marginalV relay V108V is or is notenergized, and the operation` of this relay depends on ,whether theresistance ,220 isvor -is not included in* -itscirc'ujit, v'as waspreviously explained.

From the foregoing"considerations it will Y bg Clearr that I` havedevisedasimple and eifective party yline system in which the selectiveringing is controlled entirely by Vthe connectionsio the called,branches at theY intermediate distributingV frame. It will befevidentthat any telephone number may be caused to ringen either of the twofrequencies to either yside 'of the line simply by connectingtlie'jumperto tlie proper terminalset Vof the idler block group in use.

This makes itepossible to change subscribers fromon'e party line toanother, and changey the y frequency and connections of e the ringers,if necessary, without changing-their telephone numbers.

i disconnected from the party line shown andY A QFor instance, and infurther explanation Y otthepifocess oi changing a subscribers telephonefrom onepartynlineto another, if .thegsubscriber at substation Af shouldchange his residence his telephone may be connected to any party line inthe new locality on which there is a vacancy. At the exchange the jumper205 is transferred from the idler block terminal set where it is nowconnected to a vacant terminal set 'on vthe idler block group to whichthe new party line is connected, vthe 33P terminal set. beingused incase it is vacant. Assum-V ing that this set is available and is madeuse of the telephone will'now` be connected 'ors'ervice vin itsnewlocation without fur- 'K ther change. Incase, however, t-hat the 33Pterminal set on the new idler block groupi is in use the'jumper may beconnected to any other. set of this group which is vacant and thefrequency kof the ringer, the con-` nection of the ringer to the line,or both,

telephone to, the new ringing condition. Y While I have described acertain speciiic embodiment of my invention, vI am aware that Vchangesvrand modications may be made which under certain circumstances may bedesirable. For instance, instead of Ymay be changed in order to.accommodate they e the 33 andy 50 cycle ringing current generc atorsshown and described herein, gener- Aators'may be used which deliverpositive and negative lpulsating currents, such ma-V chines being wellknown and .in extended use. It will be obvious also' that the prin-Vciples upon which party lines arevconnected up and selectively signalledmaybe employed Vwith advantage inftwoparty systems. For a two partysystem the easiestV method ot procedure is to employ but one kind ofringing current and connect the two stations on each linefrom oppositesides of the line to ground. `The marginal t,

ringing circuit selecting relay at the connector wouldl be omitted, aswould also the resistance 220 and relay 221v at-the idler block groups.The wiring ofthe idler bloc;

groups would Abe simpliiied, it being only necessaryto provide for areversal between Vthe two terminal sets l which take .Y the jumperscoming from the horizontal side In view of the above I do not wish to berestrictedv to the precise form ofthe invention disclosed Aherein butdesire. to secure and have protected by Letters Patent allvmodiiications of my invention whichmay lthereafter` bev devised, limitedonly by the Vscope of; the appended claims.

the calling linecan'operate said switch to connect withk any one of saidbranches, ringing current generators of different fre-i quency, acircuit including said third conductor andy excluding any line ortalking iso conductor involved in the connection, and mechanism in saidconnector selectively controlled over said circuit to select the propergenerator to selectivelyY signal a desired sta.- tion on the calledline.

2. In a telephone system, a calling line, a called party line, anautomatic connector switch, a plurality ot branches of the called lineaccessible to said switch, each branch comprising two line conductorsand a third conductor, means whereby a subscriber on the calling linecan operate said switch to connect with any one of said branches,ringing current generators of different electrical character, a circuitincluding said third conductor and excluding any line or talkingconductor involved in the connection, and mechanism in said connectorselectively controlled over said circuit to select lthe proper generatorto selectively signal a desired station on the called line.

3. ln a telephone system, a party line, an automatic connector switch, aplurality of branches of said line accessible to said switch, eachbranch comprising line and test conductors, a resistance included in thetest conductor of one of said branches, means for operating said switchto connect with any one of said branches, selective ringing mechanismautomatically controlled over the test conductor of the branch connectedwith, and means 'for short-circuiting said resistance thereafter toinsure the proper functioning of said test conductor.

' 4. In a.- telephone system, a party line, an automatic connectorswitch, a plurality of branches of said line accessible to said switch,each branch comprising line and test conductors, a resistance includedin the test conductors ot a plurality ot said branches,

means for operating said switch to connectv with any one of saidbranches, selective ringing mechanism automatically controlled over thetest conductor of the branch connected with, and means forshort-circuiting said resistance thereafter to insure the properfunctioning or' said test conductor.

5. In a telephone system, a party line, an automatic connector switch, aplurality of branches of said line accessible to said switch, eachbranch comprising two line conductors and a third conductor, aresistance included in the third conductor of one or" said branches,means for operating said switch to connect with any one of saidbranches, selective ringing mechanism automatically controlled over thethird conductor oi' the branch connected with, and means forshortswitch, each branch comprising -two line conductors and a thirdconductor, a resistance included in the third conductors of av pluralityor' said branches, means iter opcrating said switch to connect with anyone. of said branches, selective ringing mechanism automaticallycontrolled over the third conductor of the branch connected with, and

means for short-circuiting said resistancev ing mechanism automaticallycontrolled over the third conductor of the branch connected with, andmeans for short-circuiting said resistance after the control of said'mechanism has been exercised.

8. ln a telephone system, a party line, an automatic'connector switch, aplurality of branches 'of said line accessible to said switch, eachbranch comprising two line conductors and a third conductor, aresistance included in the third conductor of one of said branches,means for operating said connecswitch, a plurality of branches of thecalled tor to connect with any one of said branches, i

a marginal ringing current selectingrelay in said connector controlledover a circuit including the third conductorA ofthe branch connectedwith, and means for excluding the said relay and resistance from thecircuit after the control of said relay has been exercised. l e

. 9. In a telephone system, a party line, an automatic connector switch,a plurality of branches of said line accessible to said switch, eachbranch comprising two line conductors and aV third conductor, aresistance. y

included in the third conductors of a plurality of said branches, meansfor operat-.

, ing said Vconnector to connect with'any one of said branches, amarginal ringingl current selecting relayin said connector controlledover a circuit including the third conductor of the branch connectedwith,'and means for excluding theV said nrelay and resistance from theVcircuit after the control of: said relay has been exercised. n

l0. In a telephone system. a party line, an automatic connector switch,a plurality of branches of said line accessible to said switch, eachbranch comprising two line-conductors and a third conductor, aresistance included in the Ythird conductor of one of said branches,means for operating said connector to connect with any one of saidbranches, selective ringing mechanism automatically controlled over acircuitincluding the third conductor of the branch connected loo'vwitlwl, andr means :tor excluding. the said mechan sin and resistancerom'the circ-uit after the control of saidv mechanism `has Ybefallexercised! 1 1. In a telephone system, a party line, anautomatic'connectori switch, a plurality rif-branches of said lineaccessible to said switch, each branch comprising two line conductorsand a third conductor, a resistance included; in the third conductorsoit a plurality oi:'-said.l branches, means for operating'said-,connector to.. connect with any one of' said branchesw selectiveringing mecha'- nism automatically controlled over Va circuit includingthe third conductor of the branch vconnected with, and means'for estcluding the said mechanism and resistancel currentselecting relayincluded in said circuit, and controlled thereover, andmeans for short.circuiting said selecting relay by closlng said circuit 1n the connectorover a new. path.

'1S-.ln a' telephone system, a four party line, an automatic connectorswitch, as'many branches of said line accessible to said switch as thereare stationsonthe line, each branch comprising two line conductors and athird conductor, a resistance included ini thethi-rd conductors of twoof said branches,

a cutollbrelayfor said line, means for perating 4said connectort'oconnect with any one ofsaid. branches, means in` said connector forestablishing a circuit for said cutolffrelay oyer..` the third.conductor of the branch connectedfwith, al marginal ringing current.selecting relay included in saidcircuit. and controlledv thereover, alocking circuit for 'holding up the selecting relay in case thev saineis energized, another seliloclring relay initially Ienergized in. serieswith the cut off relay, and contacts on the sec'- ond selffloc'kingrelayfor .closing the cut on' relay circuit over a path excluding the windingsoffboth other relays.l

. 1 4; a telephone system, a party line,

anV automaticy connector switch, a 'plurality olybranchesof said lineaccessible to said switch', each branch comprising two line. conductorsanda third conductor, a resisi v tance. included in. thethird conductorof one. 0i?AV said branches, a cubok relay for conductor direct to thegroundedv pole ot" the exchange battery.

la. lnfa telephone. system., a tour partyline, an automatic connectorswitch, as manybranches of said line accessible. to said switch as therearestations on the line, each branch comprising. two line conductors andVa third conductor, a resistance included'-in the third conductors oftwo of saidbranches,

a cut-olf relay for said line, means for operating said connector toconnect. with. any one ot said branches, means insaid connector forestablishinga circuit for said cut-ott relay over theL third conductorof: the branch connected with, a marginal` ringing current selectingrelay included in said`circuit, la switching` relay in said. vconnectoralso included in said circuit, and contactscontrolledby said switchingrelay for connecting the said thirdv conductor vdirect tov the groundedpoleofthe eXchangefbatt-ery'. 16; In a. telephone system, a party line,an automatic connector switch, af-plurality of branches of said line`accessible to, said switch, each branch comprising two line conductors'.and a'third conductor, a resistance included inthe third conductorof oneof said branches, a vcut-oftl` relay forisa-id. line, means foroperating isaid connectorto connect with. any one. of ysaid branches,means'insaid.v connectorv forv establishing a circuit for. saidcut-olfrelay over. theY third conductor of the branch connectedv with, amarginal ringingcurrent selecting relay ineluded.V in Vsaid circuit insaid' connector, a switchingrelay in saidconnector also included in saidcircuit, and, contacts controlled by said switching relay for closingsaid circuit in theconnector. over. a` path excluding said selectingrelay. l

17. InV a telephone system, a four party: line, an automa-ticV connectorswitch, .as many branches. of said line accessible to said switch asthere are stations on the line,

.each branch lcomprising two lineY conductors and a third conductor,l aresistance included Y in thel third. conductor of two of; said branches,a cut-oft' relay for said. line, means lill included in said circuit,contacts controlled by said switching relay for closing said circuit inthe connector over a path excluding said selecting relay and its ownwinding, and parallel lool-:ing circuits for maintaining the saidselecting and switching relays energized until the connector is released18. In a telephone system, a party line, an automatic connector switch,a plurality of branches oi said line accessible to said switch, eachcomprising two line conductors and a third conductor, a resistanceincluded in the third conductor of one of said branches, a cut-off relayiior said line, means for operating said connector to connect with anyone of said branches, means in said connector for establishing a circuitfor said cut-oft relay over the third conductor of the branch connectedwith, a marginal ringing` current selecting relay included in saidcircuit and controlled thereover, means for closing said circuit in theconnector over a new pat-h excluding said selecting relay, and a relayenergized over said circuit in parallel with the said cut-ofi relay forshortcircuiting said resistance.

19. In a telephone system, a tour party line, an automatic connectorswitch, as many branches oi' said line accessible to said switch asthere are stations on the line,

each branch comprising two line conductors and a third conductor, aresistance included in the third conductors orn two olf' said branches,a cut-ofi relay for said line, means tor operating said connector toconnect with any one of said branches, means in said connector Jiorestablishing a circuit for said cut-off relay over the third conductorot the branch connected with, a marginal ringing current selecting relayincluded in said circuit, and controlled thereor'er, means for closingsaid circuit in the connector over a new path excluding said selectingrelay, and a relay energized over said circuit in parallel with the saidcut-oit" relay for shortcircuiting said resistance.l

20. In telephone system, a party line, anv automatic connector switch, aplurality of branches ot said line accessible to said switch, eachbranch comprising two lineV conductor of the branch connected with, aV

marginal ringing current selecting relay included in said circuit, aswitching relay in said connector also included in said circuit,contacts cont-rolled by said switching relay for closing said circuit inthe connector over a path excluding said selecting relay, and

establishing a circuit for said cut-0E relay.V

over the third conductor oit the branch con# nected with, a marginalringing currentselccting relay included in said circuit, a switchingrelay in said connector also included in said circuit, contactscontrolled by said switching relay for closing said circuit in theconnector over a path excluding said selecting relay, and a relayenergized over said circuit in parallel with the said cut-oit relay forshort-circuiting said resistance.

22. In a telephone system, a four party line, ringers at the stations onsaid line of two kinds connected two from each side of the line, toground, four called line branches for said line at the exchange,v athird. conductor in each branch,v a connector switch operable to connectwith any one of said branches, two rounded ringing current generators ofdi erent electrical character, selecting means in said connectorcontrolled over the third conductor of an branch connected with toselect one of said generators, a relay torthereafter connecting theungrounded side of the selected generator to a line conductor of theconnected branch, there being a reversal in the line connectionsbetweentwo of said branches and the line whereby the selected generatormay be connected to either side ot the party line depending on thebranch connected with, a

' cutbi relay for said line connected from the third conductor to theungrounded pole of the battery, and means in said switch tor connectingthe grounded pole ot the battery direct to the third conductor of anyconnected branch after the proper generator has been selected.

2S. In a telephone system, a subscribers line, automatic switchesforextending connections from or to said line, a set o nor- 'malconductors including a test conductorv over whichsaid line is reachedwhen called, a resistance in said test conductor, and means for. shortcircuiting said resistance whensaid line is busy either as a calling oras a called line.

24. In a telephone system, a subscribers line, an individual switch forextending said line when calling, a cut oli relay for said switch, a setof normal conductors over

